(1) Field of the invention
The present invention relates to a gasket having a retainer element for a reed valve integrally formed therewith, which gasket may be incorporated in a compressor for an air-conditioning system used in a vehicle such as an automobile.
(2) Description of the Related Art
For example, a well-known swash plate type compressor comprises: front and rear cylinder blocks axially combined to form a swash plate chamber therebetween, the combined cylinder blocks having a same number of cylinder bores radially formed therein and arranged with respect to the central axis thereof, the cylinder bores of the front cylinder block being aligned and registered with the cylinder bores of the rear cylinder block, respectively, with the swash plate chamber intervening therebetween; double-headed pistons slidably received in the pairs of aligned cylinder bores, respectively; front and rear housings fixed to front and rear end faces of the combined cylinder blocks through the intermediary of front and rear valve plate assemblies, respectively, the front and rear housings each forming a suction chamber and a discharge chamber together with the corresponding one of the front and rear valve plate assemblies; a rotatable drive shaft arranged so as to be axially extended through the front housing and the combined cylinder blocks: and a swash plate securely mounted on the drive shaft within the swash plate chamber and engaging with the double-headed pistons to cause these pistons to be reciprocated in the pairs of aligned cylinder bores, respectively, by the rotation of the swash plate. The front and rear cylinder blocks, the front and rear valve plates and the front and rear housings are axially and tightly assembled as an integrated unit by a plurality of long screw bolts extended therethrough.
The front and rear valve plate assemblies in particular have substantially the same construction, in that each comprises: a disc-like member having sets of a suction port and a discharge port each set of which is able to communicate with the corresponding one of the cylinder bores of the front or rear cylinder block; an inner valve sheet attached to the inner side surface of the disc-like member and having suction reed valve elements formed integrally therein, each of which is arranged so as to open and close the corresponding suction port of the disc-like member; an outer valve sheet attached to the outer side surface of the disc-like member and having discharge reed valve elements formed integrally therein, each of which is arranged so as to open and close the corresponding discharge port of the disc-like member; and a gasket attached to the outer valve sheet and hermetically engaged with an end face of a partition wall of the front or rear housing defining the suction and discharge chambers. Each of the front and rear valve plate assemblies is also provided with suction openings aligned with passages formed in the front or rear cylinder block, respectively, whereby the suction chambers formed by the front and rear housings are in communication with the swash plate chamber into which a refrigerant is introduced from an evaporator of an air-conditioning system, through a suitable inlet port formed in the combined cylinder blocks.
In the swash plate type compressor as mentioned above, the drive shaft is driven by the engine of a vehicle, such as an automobile, so that the swash plate is rotated within the swash plate chamber, and the rotational movement of the swash plate causes the double-headed pistons to be reciprocated in the pairs of aligned cylinder bores. When each piston is reciprocated in the aligned cylinder bores, a suction stroke is executed in one of the aligned cylinder bores and an compression stroke is executed in the other cylinder bore. During the suction stroke, the suction reed valve element is opened and the discharge reed valve element is closed, whereby the refrigerant is delivered from the suction chamber to the cylinder bore through the suction port. During the compression stroke, the suction reed valve element concerned is closed and the discharge reed valve element concerned is opened, whereby the delivered refrigerant is compressed and discharged from the cylinder bore into the discharge chamber, through the discharge reed valve element.
When the refrigerant is discharged through the discharge reed valve, the discharge reed valve element must be held at a given angle, to thereby prevent an excessive bending of the discharge reed valve element. Accordingly, it has been proposed that a retainer element be integrally formed in the gasket of the front or rear valve plate assembly, to provide a sloped surface on which the discharge reed valve can bear. The integral formation of the retainer elements in the gasket is carried out by a press. In this case, conventionally, the retainer element is defined by a pair of outer straight contour lines substantially included in a plane of the gasket and by a pair of inner straight contour lines disposed between the outer straight contour lines and above the plane of the gasket. In particular, the sloped bearing surface of the retainer element is extended between the inner contour lines, and each of the side walls of the retainer element is extended downward from one of the inner contour lines to the corresponding one of the outer contour lines.
During the discharge of the refrigerant, the discharge reed valve element is pressed against the sloped bearing surface of the retainer element, and thus a pressure produced by the discharged refrigerant is directly exerted upon the retainer element, as a deformation force thereof, and when the retainer element is subjected to such a deformation force, each straight contour line acts as if it were a hinge, and as a result, the conventional retainer element may be prematurely broken along the straight contour lines. Although it is possible to thicken the gasket to prevent a breakage of the retainer element, this increases the weight of the compressor and increases the production cost thereof.